The present invention relates to a transparent ink-jet recording medium for recording images by an inkjet system.
In the past, in order to record and diagnose a digital medical image, the image used to be recorded on a wet silver-salt film by wet development processing. Because the wet development requires tap water piping and others for processing, installation of a processing place is limited. Besides, the processing itself is not friendly to the environment because it discharges waste water.
Because of the above, so called dry silver-salt recording method has been developed, where image information is recorded as a latent image by light such as laser and then the image is developed by heating or the image information is recorded by heat, using thermal head. Thus, a recording method or recording device that does not require wet development processing is becoming popular.
However, although an image obtained by a recording method or recording device that does not require wet development processing was good for medical diagnosis, but does not always satisfy doctors' requirements in every respect. The inventor of the present invention has examined possible reasons for dissatisfaction and found several factors.
The first factor is that an image appears differently depending upon the light diffusion condition of the light source used for observation.
Generally, when a medical image is recorded on a recording medium and then diagnosed, using a light box (for example, film view) that is made of a fluorescent light, serving as the light source, covered with a diffusion plate, the recording medium is set on the diffusion plate of the light box and transmitted image is observed. That is, an observer observes the image under diffused light. If the condition of the light diffused by the light box is perfect diffused light, visual transmission density corresponds to diffuse transmission density. However, because the light diffused by the light box is not always ideal and perfect diffused light, the transmission density to be sensed visually is consequently a value between the diffuse transmission density and parallel transmission density. The condition of the light diffused by each light box differs from one to another and the light transmitted through each light box differs in the ratio of the diffused components to transmitted components. Because of this, what value between the diffuse transmission density and parallel transmission density is visually sensed as the image density depends upon each light box and so the image cannot be displayed in stable image quality.
Besides, if the relationship between the diffuse transmission density and parallel transmission density of a recorded image varies tremendously by image density, the ratio of the diffused components to transmitted components in the transmitted light to be observed on a light box becomes different by density. Because of the above, even if the diffuse transmission density of a test image for density gradation correction is measured and the density gradation characteristic is adjusted according to the measurement result, images cannot always be seen as intended depending upon the condition of the light diffused by the light box.
The second factor is that the recording medium fogs depending upon the light diffusion of the medium, particularly that of the medium on which no image is recorded.
Because the non-image portion (portion on which no image is recorded) of a recording medium used in the dry silver-salt recording method has higher degree of light diffusion and accordingly looks very foggy, the low-density portion of an image cannot be observed smoothly.